Electron-rich palladium regulated by cationic vacancies in CoFe layered double hydroxide boosts electrocatalytic hydrodechlorination

Palladium (Pd) is regarded as a promising electrocatalytic hydrodechlorination (EHDC) catalyst for the detoxification of halogenated phenols. Nevertheless, its intrinsic EHDC activity is seriously restricted by the hydrogen evolution reaction (HER), consuming the active hydrogen (H*) for EHDC. Here, we report a defect regulation strategy using cationic vacancies rich CoFeV-LDH with coupling ultrafine Pd nanoparticles that induces optimized electron distribution of Pd to promote EHDC. The experimental and theoretical results reveal that superior EHDC performance of Pd@CoFeV-LDH is attributed to the electron-rich Pd regulated by cationic vacancies in CoFeV-LDH support, driving facile adsorption of halogenated phenols, high water activation ability and H* selectivity for EHDC. Our findings provide a versatile defect-regulating strategy to overcome the challenge in efficiency and selectivity of EHDC process.

Purification mechanism of microbial metabolism in kitchen-oil wastewater enhanced by cationic vacancies on γ-Al2O3

The use of catalyst materials to mediate the enhancement of microbial degradation in wastewater is a new economic and energy saving breakthrough in water treatment technology. In this study, γ-Al2O3, which is commonly used as catalyst/carrier, is used as biological filler to treat kitchen-oil wastewater with low biodegradability, and the COD removal rate is about 50 %. It is found that the complexation of cationic vacancies on Al2O3 surface with extracellular polymeric substance (EPS) secreted by microorganisms in wastewater lead to the polarization of electron distribution on biofilm. The efficient degrading bacteria are enriched on reaction interface and obtain electrons to maintain electron dynamic balance by enhancing the transmembrane metabolism of pollutants. The aluminum vacancies on Al2O3 surface accelerate the microbial degradation of pollutants. The cationic vacancies in the structure of catalyst accelerate the acquisition of exogenous electrons by microorganisms without the addition of external energy, which provides a new idea for catalytic fillers to enhance wastewater degradation.